328 lines
11 KiB
Python
328 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014, 2015 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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""" This module is responsible for getting events from the DB for pagination
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and event streaming.
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The order it returns events in depend on whether we are streaming forwards or
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are paginating backwards. We do this because we want to handle out of order
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messages nicely, while still returning them in the correct order when we
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paginate bacwards.
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This is implemented by keeping two ordering columns: stream_ordering and
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topological_ordering. Stream ordering is basically insertion/received order
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(except for events from backfill requests). The topolgical_ordering is a
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weak ordering of events based on the pdu graph.
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This means that we have to have two different types of tokens, depending on
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what sort order was used:
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- stream tokens are of the form: "s%d", which maps directly to the column
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- topological tokems: "t%d-%d", where the integers map to the topological
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and stream ordering columns respectively.
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"""
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from twisted.internet import defer
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from ._base import SQLBaseStore
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from synapse.api.errors import SynapseError
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from synapse.util.logutils import log_function
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from collections import namedtuple
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import logging
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logger = logging.getLogger(__name__)
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MAX_STREAM_SIZE = 1000
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_STREAM_TOKEN = "stream"
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_TOPOLOGICAL_TOKEN = "topological"
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class _StreamToken(namedtuple("_StreamToken", "topological stream")):
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"""Tokens are positions between events. The token "s1" comes after event 1.
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s0 s1
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[0] V [1] V [2]
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Tokens can either be a point in the live event stream or a cursor going
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through historic events.
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When traversing the live event stream events are ordered by when they
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arrived at the homeserver.
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When traversing historic events the events are ordered by their depth in
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the event graph "topological_ordering" and then by when they arrived at the
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homeserver "stream_ordering".
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Live tokens start with an "s" followed by the "stream_ordering" id of the
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event it comes after. Historic tokens start with a "t" followed by the
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"topological_ordering" id of the event it comes after, follewed by "-",
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followed by the "stream_ordering" id of the event it comes after.
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"""
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__slots__ = []
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@classmethod
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def parse(cls, string):
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try:
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if string[0] == 's':
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return cls(topological=None, stream=int(string[1:]))
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if string[0] == 't':
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parts = string[1:].split('-', 1)
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return cls(topological=int(parts[0]), stream=int(parts[1]))
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except:
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pass
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raise SynapseError(400, "Invalid token %r" % (string,))
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@classmethod
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def parse_stream_token(cls, string):
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try:
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if string[0] == 's':
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return cls(topological=None, stream=int(string[1:]))
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except:
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pass
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raise SynapseError(400, "Invalid token %r" % (string,))
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def __str__(self):
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if self.topological is not None:
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return "t%d-%d" % (self.topological, self.stream)
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else:
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return "s%d" % (self.stream,)
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def lower_bound(self):
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if self.topological is None:
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return "(%d < %s)" % (self.stream, "stream_ordering")
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else:
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return "(%d < %s OR (%d == %s AND %d < %s))" % (
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self.topological, "topological_ordering",
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self.topological, "topological_ordering",
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self.stream, "stream_ordering",
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)
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def upper_bound(self):
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if self.topological is None:
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return "(%d >= %s)" % (self.stream, "stream_ordering")
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else:
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return "(%d > %s OR (%d == %s AND %d >= %s))" % (
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self.topological, "topological_ordering",
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self.topological, "topological_ordering",
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self.stream, "stream_ordering",
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)
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class StreamStore(SQLBaseStore):
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@log_function
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def get_room_events_stream(self, user_id, from_key, to_key, room_id,
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limit=0, with_feedback=False):
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# TODO (erikj): Handle compressed feedback
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current_room_membership_sql = (
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"SELECT m.room_id FROM room_memberships as m "
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"INNER JOIN current_state_events as c ON m.event_id = c.event_id "
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"WHERE m.user_id = ? AND m.membership = 'join'"
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)
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# We also want to get any membership events about that user, e.g.
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# invites or leave notifications.
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membership_sql = (
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"SELECT m.event_id FROM room_memberships as m "
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"INNER JOIN current_state_events as c ON m.event_id = c.event_id "
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"WHERE m.user_id = ? "
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)
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if limit:
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limit = max(limit, MAX_STREAM_SIZE)
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else:
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limit = MAX_STREAM_SIZE
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# From and to keys should be integers from ordering.
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from_id = _StreamToken.parse_stream_token(from_key)
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to_id = _StreamToken.parse_stream_token(to_key)
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if from_key == to_key:
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return defer.succeed(([], to_key))
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sql = (
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"SELECT e.event_id, e.stream_ordering FROM events AS e WHERE "
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"(e.outlier = 0 AND (room_id IN (%(current)s)) OR "
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"(event_id IN (%(invites)s))) "
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"AND e.stream_ordering > ? AND e.stream_ordering <= ? "
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"ORDER BY stream_ordering ASC LIMIT %(limit)d "
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) % {
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"current": current_room_membership_sql,
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"invites": membership_sql,
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"limit": limit
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}
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def f(txn):
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txn.execute(sql, (user_id, user_id, from_id.stream, to_id.stream,))
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rows = self.cursor_to_dict(txn)
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ret = self._get_events_txn(
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txn,
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[r["event_id"] for r in rows],
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get_prev_content=True
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)
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if rows:
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key = "s%d" % max([r["stream_ordering"] for r in rows])
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else:
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# Assume we didn't get anything because there was nothing to
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# get.
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key = to_key
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return ret, key
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return self.runInteraction("get_room_events_stream", f)
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@log_function
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def paginate_room_events(self, room_id, from_key, to_key=None,
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direction='b', limit=-1,
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with_feedback=False):
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# TODO (erikj): Handle compressed feedback
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# Tokens really represent positions between elements, but we use
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# the convention of pointing to the event before the gap. Hence
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# we have a bit of asymmetry when it comes to equalities.
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args = [room_id]
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if direction == 'b':
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order = "DESC"
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bounds = _StreamToken.parse(from_key).upper_bound()
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if to_key:
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bounds = "%s AND %s" % (
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bounds, _StreamToken.parse(to_key).lower_bound()
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)
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else:
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order = "ASC"
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bounds = _StreamToken.parse(from_key).lower_bound()
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if to_key:
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bounds = "%s AND %s" % (
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bounds, _StreamToken.parse(to_key).upper_bound()
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)
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if int(limit) > 0:
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args.append(int(limit))
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limit_str = " LIMIT ?"
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else:
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limit_str = ""
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sql = (
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"SELECT * FROM events"
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" WHERE outlier = 0 AND room_id = ? AND %(bounds)s"
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" ORDER BY topological_ordering %(order)s,"
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" stream_ordering %(order)s %(limit)s"
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) % {
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"bounds": bounds,
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"order": order,
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"limit": limit_str
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}
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def f(txn):
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txn.execute(sql, args)
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rows = self.cursor_to_dict(txn)
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if rows:
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topo = rows[-1]["topological_ordering"]
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toke = rows[-1]["stream_ordering"]
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if direction == 'b':
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# Tokens are positions between events.
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# This token points *after* the last event in the chunk.
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# We need it to point to the event before it in the chunk
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# when we are going backwards so we subtract one from the
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# stream part.
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toke -= 1
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next_token = str(_StreamToken(topo, toke))
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else:
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# TODO (erikj): We should work out what to do here instead.
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next_token = to_key if to_key else from_key
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events = self._get_events_txn(
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txn,
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[r["event_id"] for r in rows],
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get_prev_content=True
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)
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return events, next_token,
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return self.runInteraction("paginate_room_events", f)
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def get_recent_events_for_room(self, room_id, limit, end_token,
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with_feedback=False):
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# TODO (erikj): Handle compressed feedback
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sql = (
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"SELECT stream_ordering, topological_ordering, event_id FROM events "
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"WHERE room_id = ? AND stream_ordering <= ? AND outlier = 0 "
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"ORDER BY topological_ordering DESC, stream_ordering DESC LIMIT ? "
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)
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def f(txn):
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txn.execute(sql, (room_id, end_token, limit,))
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rows = self.cursor_to_dict(txn)
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rows.reverse() # As we selected with reverse ordering
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if rows:
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# Tokens are positions between events.
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# This token points *after* the last event in the chunk.
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# We need it to point to the event before it in the chunk
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# since we are going backwards so we subtract one from the
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# stream part.
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topo = rows[0]["topological_ordering"]
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toke = rows[0]["stream_ordering"] - 1
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start_token = str(_StreamToken(topo, toke))
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token = (start_token, end_token)
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else:
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token = (end_token, end_token)
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events = self._get_events_txn(
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txn,
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[r["event_id"] for r in rows],
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get_prev_content=True
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)
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return events, token
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return self.runInteraction("get_recent_events_for_room", f)
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def get_room_events_max_id(self):
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return self.runInteraction(
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"get_room_events_max_id",
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self._get_room_events_max_id_txn
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)
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def _get_room_events_max_id_txn(self, txn):
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txn.execute(
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"SELECT MAX(stream_ordering) as m FROM events"
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)
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res = self.cursor_to_dict(txn)
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logger.debug("get_room_events_max_id: %s", res)
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if not res or not res[0] or not res[0]["m"]:
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return "s0"
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key = res[0]["m"]
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return "s%d" % (key,)
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